<title>Conditional Expressions</title>

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<h1>Conditional Expressions.</h1>
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<p>


We have a short-hand construct for some <b>if ... else ...</b> constructs.<p>
Consider the following two examples.
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<th>Example 1</th>
<th>Example 2</th>
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<pre>

  if ( x == 1 ) 
    y = 10;
  else
    y = 20;
    
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<pre>

  y = (x == 1) ? 10 : 20;  

</pre>
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<p>
These examples both perform the same function. If x is 1 then y becomes 10
else y becomes 20. The example on the right evaluates the first expression 
'(x ==1 )' and if <b>true</b> evaluates the second '10'. If <b>false</b> the
third is evaluated. Here is another example.
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<th>Example 1</th>
<th>Example 2</th>
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<pre>

 if ( x == 1 ) 
   puts("take car"); 
 else
   puts("take bike");  
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<pre>

 (x == 1) ? puts("take car") : puts("take bike"); 
                                                  
    or

 puts( (x == 1) ? "take car" : "take bike");
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<p>
It has been said that the compiler can create more efficent code from
a <b>conditional expression</b> possibly at the expence of readable code.
Unless you are writing time critical code (and lets face it, thats unlikely)
the more efficent code is not much of a reason to use this construct.
I feel that it has its uses, but should not be lost into some complex
statement,
but, since when did C programmers worry if anyone else could read their 
code ;-)
<p> 
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<h2>See also:</h2>
<ul>
<li><a href="if.html">if</a> keyword.
<li><a href="switch.html">switch</a> keyword.
<li><a href="idioms.html#printf">A use within printf.</a>.
</ul>

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<address><a href="../../address.html">Martin Leslie</a> 
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